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  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
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    <script>
      // 不同数据类型
      console.log(true === true);
      console.log(true === 1);
      console.log(null === undefined);

      console.log(NaN != NaN);
      console.log(NaN !== NaN);

      //
    </script>
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</html>
